In numerous types of situations and environments it is desirable or necessary to provide a sheet which carries a hidden message or indicia. For example, in some merchandizing schemes a hidden message is present on a sheet and can be read only after a coating is removed by scratch removal of the coating or by some other method of removal of the coating. Some types of hidden messages on a sheet appear only after a chemical solution is applied to the sheet. Some types of hidden messages which are carried by a sheet appear only after a reaction occurs in the message when the sheet is subjected to artificial or natural light. Some types of hidden messages which are carried by a sheet are made to appear only after the sheet is subjected to a significant temperature change. Some types of hidden messages which are carried by a sheet are made readable only when observed in a special kind of light rays. Some types of hidden messages which are carried upon a sheet are made visible for reading only when viewed through special optics. Several other methods for applying and for reading hidden messages have been created. However, all of the known methods for applying and/or for viewing hidden messages have been relatively expensive to apply and/or inconvenient to use.
It is therefore an object of this invention to provide a method of applying a hidden message to a sheet by which the process is relatively inexpensive.
Another object of this invention is to provide a sheet with a hidden message in which the hidden message can be readily observed by the use of normal light rays.
Another object of this invention is to provide such a method which creates high quality products.
Other objects and advantages of this invention reside in the construction and application of parts, the combination thereof, the method of production and the mode of use, as will become more apparent from the following description.